RESUMO
Salmonella persists for a long time in B cells; however, the mechanism(s) through which infected B cells avoid effector CD8 T cell responses has not been characterized. In this study, we show that Salmonella infects and survives within all B1 and B2 cell subpopulations. B cells are infected with a Salmonella typhimurium strain expressing an ovalbumin (OVA) peptide (SIINFEKL) to evaluate whether B cells process and present Salmonella antigens in the context of MHC-I molecules. Our data showed that OVA peptides are presented by MHC class I K(b)-restricted molecules and the presented antigen is generated through proteasomal degradation and vacuolar processing. In addition, Salmonella-infected B cells express co-stimulatory molecules such as CD40, CD80, and CD86 as well as inhibitory molecules such as PD-L1. Thus, the cross-presentation of Salmonella antigens and the expression of activation molecules suggest that infected B cells are able to prime and activate specific CD8(+) T cells. However, the Salmonella infection-stimulated expression of PD-L1 suggests that the PD-1/PD-L1 pathway may be involved in turning off the cytotoxic effector response during Salmonella persistent infection, thereby allowing B cells to become a reservoir for the bacteria.
Assuntos
Linfócitos B/imunologia , Linfócitos B/metabolismo , Antígeno B7-H1/genética , Regulação da Expressão Gênica , Infecções por Salmonella/imunologia , Infecções por Salmonella/metabolismo , Salmonella/imunologia , Animais , Apresentação de Antígeno/imunologia , Antígenos de Bactérias/imunologia , Antígenos de Bactérias/metabolismo , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/metabolismo , Subpopulações de Linfócitos B/microbiologia , Linfócitos B/microbiologia , Antígeno B7-H1/metabolismo , Transporte Biológico , Apresentação Cruzada/imunologia , Modelos Animais de Doenças , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Ativação Linfocitária/imunologia , Camundongos , Salmonella typhimurium/imunologia , Vacúolos/imunologia , Vacúolos/metabolismoRESUMO
The present paper is an overview of the primary events that are associated with the histoplasmosis immune response in the murine model. Valuable data that have been recorded in the scientific literature have contributed to an improved understanding of the clinical course of this systemic mycosis, which is caused by the dimorphic fungus Histoplasma capsulatum. Data must be analyzed carefully, given that misinterpretation could be generated because most of the available information is based on experimental host-parasite interactions that used inappropriate proceedings, i.e., the non-natural route of infection with the parasitic and virulent fungal yeast-phase, which is not the usual infective phase of the etiological agent of this mycosis. Thus, due to their versatility, complexity, and similarities with humans, several murine models have played a fundamental role in exploring the host-parasite interaction during H. capsulatum infection.